March 2, 2012 AT 7:50 am

New electronics reference sheet

Our microprocessor reference sheet has been a great success and a valuable resource for many DIY hackers out there. We are proud to introduce an updated version, a second page with ATMegaXX4/Sanguino and a brand new
electronics reference sheet.

We now also have the reference sheet in bigger resolutions suitable for printing on both A4 and A3 paper.

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9 Comments

To be honest, I don’t think that there’s a huge amount of value in the sheet with the semiconductor pinouts.

This might give beginners the false impression that every FET or BJT or regulator IC in a particular package type always has the same pinout – which isn’t true.

It’s good to teach beginners good habits to save problems – like looking up the datasheet to find out the pinout and specifically check it for the specific device you’re using.

If you just assume that every, say, TO92 transistor always has the same pinout then eventually you’re going to be frustrated one day when you can’t get your device to work because you’ve got a different one and you didn’t check.

If the table of common semiconductor pinouts listed some common specific semiconductor devices specifically by name and gave their pinouts then that might work better – for example, LM78xx regulators have these pinouts, but the LD1117xx TO-220 has this different pinout, and the very common BC54x series TO-92 BJTs have a pinout like so, but the 2N23904 has the opposite pinout.

Just a heads up that the PNP on that diagram isn’t correct. Not trying to point any fingers, I’d just hate to see people misled by something that they’re relying on to clarify things. The emitter and collector aren’t labelled properly (they should be switched with the C on top) and the load is on the wrong side.

If you switch the arrow pointing in (on the C) and move it to the top instead (on E) this would be correct including the load location.

Also … you have to be very careful with surface mount LEDs. The markings usually indicate the Cathode (95% of the time) but I’ve been burned by it being the anode as well. Once I even had two LEDs, red and green, from the same manufacturer in exactly the same series (part numbers were 1 apart) and one one the marking meant anode on the other cathode. Sigh. :/

But still … great job on the poster, just need to clarify the PNP a bit.